The 23-year-old has signed a one-year deal with the Silkmen after impressing on trial.
Versatile defender Kennedy has spent the last two weeks with the club and produced an impressive performance in the friendly game with Sky Bet Championship side Derby County.
Kennedy began his career with Manchester City before joining Leicester City in 2013, initially on loan then permanently.
After two years with the Foxes he joined Motherwell at the start of the 2015/16 season and made twenty-five appearances for the club before leaving earlier this year to join AFC Fylde where he helped the club seal promotion from the National League North.